1. Field of the Invention
This invention relates to an optical apparatus including an imaging device using an extended surface optical element and a variable optical-property reflecting mirror, or including a variable optical-property element, a variable optical-property mirror, or a combination of the variable optical-property element with the variable optical-property mirror.
2. Description of Related Art
For a conventional, variable optical-property element such as a variable focal-length lens or a variable focal-length lens, a description will be given of the variable focal-length lens as an example. In an optical system, an extended surface optical element may be used. The extended surface of the extended surface optical element refers to any surface which has a shape such as a spherical, planar, or rotational symmetrical aspherical surface; a spherical, planar, or rotational symmetrical aspherical surface which is decentered with respect to the optical axis; an aspherical surface with symmetrical surfaces; an aspherical surface with only one symmetrical surface; an aspherical surface with no symmetrical surface; a free-formed surface; a surface with a nondifferentiable point or line; etc. In optical systems having used optical elements with the extended surfaces, an optical system utilizing the reflection of the extended surface has the merit that chromatic aberration is not produced. This optical system, however, has the disadvantage that in the case where the shape of the extended surface is abnormal, when the optical element is moved for zooming and focusing operations, a mechanical structure such as a moving mechanism becomes complicated.
A conventional digital camera, as shown in FIG. 1, has been manufactured by assembling components such as plastic lenses PL, a stop D, a solenoid FS for focusing, a shutter S, a charge-coupled solid-state image sensor CCD, a signal processing circuit PC, and a memory M. Consequently, the number of parts is increased and an assembly becomes troublesome. Thus, there are limits to a compact design, accuracy improvement, and cost reduction of the camera.
Furthermore, in general, the plastic lens has a tendency that its refractive index and shape change with temperature and humidity, and thus imaging performance is degraded by temperature change. In this way, glass lenses are, chiefly used, and a lightweight design, accuracy improvement, and cost reduction of the camera are highly limited.